Just wanted to chime in and say good luck on your project. I love the 74 set, as it was the first set that my buddies and I tried to complete the summer before we entered High School (after that all our money went to cars and girls)
You definitely have some challenges there...Gonzalo Marquez comes to mind, along with a pricey Thurman Munson. Horacio Pina used to be a lot tougher until a couple of people had some private signings with him. I was curious though, are you also looking to get the traded cards from that set signed as well?
Anyway, good luck!